Synthesis gas production with an adjustable H{sub 2}/CO ratio through the coal gasification process: effects of coal ranks and methane addition

Direct production of synthesis gas using coal as a cheap feedstock is attractive but challenging due to its low H{sub 2}/CO ratio of generated synthesis gas. Three typical U.S. coals of different ranks were tested in a 2.5 in. coal gasifier to investigate their gasification reactivity and adjustabil...

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Bibliographic Details
Published in:Energy & fuels 2008-05, Vol.22 (3)
Main Authors: Yan Cao, Zhengyang Gao, Jing Jin, Hongchang Zhou, Marten Cohron, Houying Zhao, Hongying Liu, Weiping Pan
Format: Article
Language:English
Subjects:
01 COAL, LIGNITE, AND PEAT
CATALYTIC EFFECTS
CHARS
COAL GASIFICATION
COAL RANK
COPROCESSING
METHANE
REACTIVITY
SYNTHESIS GAS
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Summary:Direct production of synthesis gas using coal as a cheap feedstock is attractive but challenging due to its low H{sub 2}/CO ratio of generated synthesis gas. Three typical U.S. coals of different ranks were tested in a 2.5 in. coal gasifier to investigate their gasification reactivity and adjustability on H{sub 2}/CO ratio of generated synthesis gas with or without the addition of methane. Tests indicated that lower-rank coals (lignite and sub-bituminous) have higher gasification reactivity than bituminous coals. The coal gasification reactivity is correlated to its synthesis-gas yield and the total percentage of H{sub 2} and CO in the synthesis gas, but not to the H{sub 2}/CO ratio. The H{sub 2}/CO ratio of coal gasification was found to be correlated to the rank of coals, especially the H/C ratio of coals. Methane addition into the dense phase of the pyrolysis and gasification zone of the cogasification reactor could make the best use of methane in adjusting the H{sub 2}/CO ratio of the generated synthesis gas. The maximum methane conversion efficiency, which was likely correlated to its gasification reactivity, could be achieved by 70% on average for all tested coals. The actual catalytic effect of generated coal chars on methane conversion seemed coal-dependent. The coal-gasification process benefits from methane addition and subsequent conversion on the adjustment of the H{sub 2}/CO ratio of synthesis gas. The methane conversion process benefits from the use of coal chars due to their catalytic effects. This implies that there were likely synergistic effects on both. 25 refs., 3 figs., 3
ISSN:0887-0624
1520-5029